Cardiac surgery is one of the most complex specialties in medicine, akin to a complex sociotechnical system. Patient outcomes are vulnerable to surgical flow disruptions (SFDs), a source of preventable harm. Healthcare providers' (HCPs) sympathetic activation secondary to emotional states represent an underappreciated source of SFDs. This study's objective was to demonstrate the feasibility of detecting elevated sympathetic nervous system (SNS) activity as a proxy for emotional distress associated with a medication error using heart rate variability (HRV) analysis. After obtaining informed consent, audio/video and HRV data were captured intraoperatively during cardiac surgery from multiple HCPs. Following a critical medication administration error by the anesthesiologist in-training, the attending anesthesiologists' recorded HRV data was analyzed using pyphysio, an open-source signal analysis package, to identify events precipitating this near-miss event. We considered elevated low-frequency/high-frequency (LF/HF) HRV ratio (normal value <2) as a primary indicator of SNS activity and emotional distress. A heightened SNS response by the attending anesthesiologist, observed as an LF/HF ratio value of 3.39, was detected prior to the near-miss event. The attending anesthesiologist confirmed a state of significant SNS activity/distress induced by task-irrelevant environmental factors, which led to a temporarily ineffective mental model. Qualitative analysis of audio/video recordings revealed that SNS activation coincided with an argument over operating room management causing SFD. This preliminary study confirms the feasibility of recognizing potentially detrimental psychophysiological states during cardiac surgery in the wild using HRV analysis. To our knowledge, this is the first case demonstrating SNS activation coinciding with self-reported and observable emotional distress during live surgery using HRV. Irrespective of the HCP's expertise, transient but intense emotional changes may disrupt attention processes leading to SFDs and preventable errors. This work supports the possibility to detect real-time SNS activation, which could enable interventions to proactively mitigate errors. Additional studies on our large database of surgical cases are underway to confirm this observation.
Mario Gaudino, Pieter A Kappetein, Antonino Di Franco, Emilia Bagiella, Deepak L Bhatt, Andreas Boening, Mary E Charlson, Marcus Flather, Annetine C Gelijns, Frederick Grover, Stuart J Head, Peter Jüni, Andre Lamy, Marissa Miller, Alan Moskowitz, Wilko Reents, Laurie A Shroyer, David P Taggart, Derrick Y Tam, Marco A Zenati, and Stephen E Fremes. 2020. “Randomized Trials in Cardiac Surgery: JACC Review Topic of the Week.” J Am Coll Cardiol, 75, 13, Pp. 1593-1604.Abstract
Compared with randomized controlled trials (RCTs) in medical specialties, RCTs in cardiac surgery face specific issues. Individual and collective equipoise, rapid evolution of the surgical techniques, as well as difficulties in obtaining funding, and limited education in clinical epidemiology in the surgical community are among the most important challenges in the design phase of the trial. Use of complex interventions and learning curve effect, differences in individual operators' expertise, difficulties in blinding, and slow recruitment make the successful completion of cardiac surgery RCTs particularly challenging. In fact, over the course of the last 20 years, the number of cardiac surgery RCTs has declined significantly. In this review, a team of surgeons, trialists, and epidemiologists discusses the most important challenges faced by RCTs in cardiac surgery and provides a list of suggestions for the successful design and completion of cardiac surgery RCTs.
Monitoring healthcare providers' cognitive workload during surgical procedures can provide insight into the dynamic changes of mental states that may affect patient clinical outcomes. The role of cognitive factors influencing both technical and non-technical skill are increasingly being recognized, especially as the opportunities to unobtrusively collect accurate and sensitive data are improving. Applying sensors to capture these data in a complex real-world setting such as the cardiac surgery operating room, however, is accompanied by myriad social, physical, and procedural constraints. The goal of this study was to investigate the feasibility of overcoming logistical barriers in order to effectively collect multi-modal psychophysiological inputs via heart rate (HR) and near-infrared spectroscopy (NIRS) acquisition in the real-world setting of the operating room. The surgeon was outfitted with HR and NIRS sensors during aortic valve surgery, and validation analysis was performed to detect the influence of intra-operative events on cardiovascular and prefrontal cortex changes. Signals collected were significantly correlated and noted intra-operative events and subjective self-reports coincided with observable correlations among cardiovascular and cerebral activity across surgical phases. The primary novelty and contribution of this work is in demonstrating the feasibility of collecting continuous sensor data from a surgical team member in a real-world setting.
Background. The most commonly used subjective assessment of perceived cognitive load, the NASA Task Load Index (TLX), has proven valuable in measuring individual load among general populations. The surgery task load index (SURG-TLX) was developed and validated to measure cognitive load specifically among individuals within a surgical team. Notably, the TLX lacks temporal sensitivity in its typical retrospective administration. Objective. This study sought to expand the utility of SURG-TLX by investigating individual measures of cognitive load over time during cardiac surgery, and the relationship between individual and team measures of cognitive load and proxies for surgical complexity. Materials & Methods. SURG-TLX was administered retrospectively in the operating room immediately following each case to approximate cognitive load before, during, and after cardiopulmonary bypass for cardiac surgery team members (surgeon, anesthesiologist, and perfusionist). Correlations were calculated to determine the relationship of individual and team measures of cognitive load over the entire procedure with bypass length and surgery length. Results. Results suggest that perceived cognitive load varies throughout the procedure such that cognitive load during bypass significantly differs compared to before or after bypass, across all 3 roles. While on bypass, results show that anesthesiologists experience significantly lower levels of perceived cognitive load than both surgeons and perfusionists. Correlational analyses reveal that perceived cognitive load of both the surgeon and the team had significant positive associations with bypass length and surgery length. Conclusion. Our findings support the utility of SURG-TLX in real cardiac cases as a measure of cognitive load over time, and on an individual and team-wide basis.
If a perfusionist weans a patient off the heart lung machine (HLM) and the anesthesiologist has not re-started the ventilator, the patient will become hypoxic. The objective of this project was to create a redundant safety system of verbal and electronic communication to prevent failure to ventilate errors after cardiopulmonary bypass. This objective could be realized by building an electronic communication bridge directly between the HLM and ventilator. A software application was created to retrieve and interpret data from the pump and ventilator and trigger a programmed smart alarm. The software is able to interpret data from the pump and ventilator. When both are off simultaneously (defined as a pump flow of 0 L/min with a respiratory rate of 0 breaths/min), the application will raies an alarm. Communication between a pump and ventilator is possible, enabling the deployment of a safety system that could exist in the operating room (OR) as a standalone alarm. A device dataset can be used to optimize clinical performance of the alarm. The application could also be integrated into smart checklists and computer-assisted OR process models that are currently in development.
Cognitive workload data of members of the cardiac surgery team can be measured intraoperatively and stored for later analysis. We present a case of a near-miss (medication error) that underwent root cause analysis using workload data. Heart rate variability data, representing workload levels, were collected from the attending surgeon, attending anesthesiologist, and lead perfusionist using wireless heart rate monitors. An episode of cognitive overload of the anesthesiologist due to a distractor was associated with the preventable error. Additional studies are needed to better understand the role of psychophysiological data in enhancing surgical patient safety.
BACKGROUND: Organ-mounted robots adhere to the surface of a mobile organ as a platform for minimally invasive interventions, providing passive compensation of physiological motion. This approach is beneficial during surgery on the beating heart. Accurate localization in such applications requires accounting for the heartbeat and respiratory motion. Previous work has described methods for modeling quasi-periodic motion of a point and registering to a static preoperative map. The existing techniques, while accurate, require several respiratory cycles to converge.
METHODS: This paper presents a general localization technique for this application, involving function approximation using radial basis function (RBF) interpolation.
RESULTS: In an experiment in the porcine model in vivo, the technique yields mean localization accuracy of 1.25 mm with a 95% confidence interval of 0.22 mm.
CONCLUSIONS: The RBF approximation provides accurate estimates of robot location instantaneously.
The operating room (OR) is a high-risk and complex environment, where multiple specialized professionals work as a team to effectively care for patients in need of surgical interventions. Surgical tasks impose high cognitive demands on OR staff and cognitive overload may have deleterious effects on team performance and patient safety. The aim of the present study was to investigate the feasibility and describe a novel methodological approach to characterize dynamic changes in team cognitive load by measuring synchronization and entropy of heart rate variability parameters during real-life cardiac surgery. Cognitive load was measured by capturing interbeat intervals (IBI) from three team members (surgeon, anesthesiologist and perfusionist) using an unobtrusive wearable heart rate sensor and transmitted in real-time to a smartphone application. Clinical data and operating room audio/video recordings were also collected to provide behavioral and contextual information. We developed symbolic representations of the transient cognitive state of individual team members (Individual Cognitive State - ICS), and overall team (Team Cognitive State - TCS) by comparing IBI data from each team member with themselves and with others. The distribution of TCS symbols during surgery enabled us to display and analyze temporal states and dynamic changes of team cognitive load. Shannon's entropy was calculated to estimate the changing levels of team organization and to detect fluctuations resulting from a variety of cognitive demands and/or specific situations (e.g. medical error, emergency, flow disruptions). An illustrative example from a real cardiac surgery team shows how cognitive load patterns shifted rapidly after an actual near-miss medication event, leading the team to a more organized and synchronized state. The methodological approach described in this study provides a measurement technique for the assessment of team physiological synchronization, which can be applied to many other team-based environments. Future research should gather additional validity evidence to support the proposed methods for team cognitive load measurement.
Traditionally, blood flow rates on cardiopulmonary bypass are based primarily on a formula that matches cardiac index to the patient's body surface area (BSA). However, Ranucci and associates in the Goal-Directed Perfusion Trial (GIFT) trial have shown that coupling the BSA with delivery of oxygen (DO2), known as goal-directed perfusion (GDP), may be a safer approach to determine appropriate blood flows. The objective of this study was to create a GDP reference tool that would allow perfusionists to quickly determine the lowest acceptable blood flow needed to provide a patient of any BSA with a satisfactory DO2 without the need for additional dedicated technology. We approached this problem by deriving a formula for flow (L/min), based on BSA, oxygen content of the blood, and a minimum DO2 of 280 mL·min-1m-2. A quick reference GDP chart was created based on the derived formula, requiring only the patient's BSA and hemoglobin level to determine a safe minimum flow rate. The proposed tool allows any cardiac surgery center to adopt the GDP technique, even in the absence of instantaneous DO2 monitoring equipment.
BACKGROUND: The saphenous-vein graft is the most common conduit for coronary-artery bypass grafting (CABG). The influence of the vein-graft harvesting technique on long-term clinical outcomes has not been well characterized.
METHODS: We randomly assigned patients undergoing CABG at 16 Veterans Affairs cardiac surgery centers to either open or endoscopic vein-graft harvesting. The primary outcome was a composite of major adverse cardiac events, including death from any cause, nonfatal myocardial infarction, and repeat revascularization. Leg-wound complications were also evaluated.
RESULTS: A total of 1150 patients underwent randomization. Over a median follow-up of 2.78 years, the primary outcome occurred in 89 patients (15.5%) in the open-harvest group and 80 patients (13.9%) in the endoscopic-harvest group (hazard ratio, 1.12; 95% confidence interval [CI], 0.83 to 1.51; P=0.47). A total of 46 patients (8.0%) in the open-harvest group and 37 patients (6.4%) in the endoscopic-harvest group died (hazard ratio, 1.25; 95% CI, 0.81 to 1.92); myocardial infarctions occurred in 34 patients (5.9%) in the open-harvest group and 27 patients (4.7%) in the endoscopic-harvest group (hazard ratio, 1.27; 95% CI, 0.77 to 2.11), and revascularization occurred in 35 patients (6.1%) in the open-harvest group and 31 patients (5.4%) in the endoscopic-harvest group (hazard ratio, 1.14; 95% CI, 0.70 to 1.85). Leg-wound infections occurred in 18 patients (3.1%) in the open-harvest group and in 8 patients (1.4%) in the endoscopic-harvest group (relative risk, 2.26; 95% CI, 0.99 to 5.15).
CONCLUSIONS: Among patients undergoing CABG, we did not find a significant difference between open vein-graft harvesting and endoscopic vein-graft harvesting in the risk of major adverse cardiac events. (Funded by the Cooperative Studies Program, Office of Research and Development, Department of Veterans Affairs; REGROUP ClinicalTrials.gov number, NCT01850082 .).
BACKGROUND: Organ-mounted robots address the problem of beating-heart surgery by adhering to the heart, passively providing a platform that approaches zero relative motion. Because of the quasi-periodic deformation of the heart due to heartbeat and respiration, registration must address not only spatial registration but also temporal registration.
METHODS: Motion data were collected in the porcine model in vivo (N = 6). Fourier series models of heart motion were developed. By comparing registrations generated using an iterative closest-point approach at different phases of respiration, the phase corresponding to minimum registration distance is identified.
RESULTS: The spatiotemporal registration technique presented here reduces registration error by an average of 4.2 mm over the 6 trials, in comparison with a more simplistic static registration that merely averages out the physiological motion.
CONCLUSIONS: An empirical metric for spatiotemporal registration of organ-mounted robots is defined and demonstrated using data from animal models in vivo.
To address the, currently unmet, need for intra-operative safety-critical cognitive support in cardiac surgery, we have developed, validated, and implemented a series of customized checklists to address intra-operative emergencies, using a simulated operative setting. These crisis checklists are designed to provide cognitive and communication support to the operative team to reduce the likelihood of adverse events and improve adherence to best-practice guidelines. We recruited a number of content specialists including members of the hospital safety network and intraoperative cardiac surgery team members, and utilized a Delphi consensus method to develop procedure-specific guidelines for select intraoperative crises. Cardiac surgery team members were subsequently trained on utilizing the developed checklists, performed operative simulations, and were surveyed to determine checklist facility and effectiveness. We developed and validated five checklists for the following cardiac surgery crisis scenarios: (a) Cardiopulmonary Bypass Failure; (b) Systemic Air Embolism; (c) Venous Air Lock; (d) Protamine Reaction; Heparin Resistance. Upon initiation of the crisis management, a crew resource management approach was triggered. A member of the operative team was designated as the "reader" for each scenario to guide the team through the process. After training, 89% of operative team members surveyed indicated that they would like the crisis checklist to be used if they had one of these events occurring to them. Crisis management challenges members of the cardiac surgery team in reasoning accurately and according to best practice during periods of high cognitive workload and psychological stress. These crisis checklists were developed, validated, and simulated with the goal of supporting human performance and shared mental models in the clinical setting.
In the surgical setting, team members constantly deal with a high-demand operative environment that requires simultaneously processing a large amount of information. In certain situations, high demands imposed by surgical tasks and other sources may exceed team member's cognitive capacity, leading to cognitive overload which may place patient safety at risk. In the present study, we describe a novel approach to integrate an objective measure of team member's cognitive load with procedural, behavioral and contextual data from real-life cardiac surgeries. We used heart rate variability analysis, capturing data simultaneously from multiple team members (surgeon, anesthesiologist and perfusionist) in a real-time and unobtrusive manner. Using audio-video recordings, behavioral coding and a hierarchical surgical process model, we integrated multiple data sources to create an interactive surgical dashboard, enabling the analysis of the cognitive load imposed by specific steps, substeps and/or tasks. The described approach enables us to detect cognitive load fluctuations over time, under specific conditions (e.g. emergencies, teaching) and in situations that are prone to errors. This in-depth understanding of the relationship between cognitive load, task demands and error occurrence is essential for the development of cognitive support systems to recognize and mitigate errors during complex surgical care in the operating room.
Procedural flow disruptions secondary to interruptions play a key role in error occurrence during complex medical procedures, mainly because they increase mental workload among team members, negatively impacting team performance and patient safety. Since certain types of interruptions are unavoidable, and consequently the need for multitasking is inherent to complex procedural care, this field can benefit from an intelligent system capable of identifying in which moment flow interference is appropriate without generating disruptions. In the present study we describe a novel approach for the identification of tasks imposing low cognitive load and tasks that demand high cognitive effort during real-life cardiac surgeries. We used heart rate variability analysis as an objective measure of cognitive load, capturing data in a real-time and unobtrusive manner from multiple team members (surgeon, anesthesiologist and perfusionist) simultaneously. Using audio-video recordings, behavioral coding and a hierarchical surgical process model, we integrated multiple data sources to create an interactive surgical dashboard, enabling the identification of specific steps, substeps and tasks that impose low cognitive load. An interruption management system can use these low demand situations to guide the surgical team in terms of the appropriateness of flow interruptions. The described approach also enables us to detect cognitive load fluctuations over time, under specific conditions (e.g. emergencies) or in situations that are prone to errors. An in-depth understanding of the relationship between cognitive overload states, task demands, and error occurrence will drive the development of cognitive supporting systems that recognize and mitigate errors efficiently and proactively during high complex procedures.
OBJECTIVE: To compare mitral valve repair (MVRepair) and mitral valve replacement (MVReplace) trends in the Veterans Affairs (VA) Surgical Quality Improvement Program.
METHODS: Trends were compared by bivariate analyses, followed by backward stepwise selection and multivariable logistic modeling to determine the effect of preoperative comorbidities and facility-level factors on MVRepair (vs MVReplace) rate. A subgroup analysis focused on patients who underwent elective surgery for isolated primary degenerative mitral regurgitation. Propensity matching was done in the overall and primary degenerative cohorts.
RESULTS: From October 2000 to October 2013, 4165 veterans underwent MVRepair (n = 2408) or MVReplace (n = 1757) for MV disease of any cause at 40 VA medical centers (procedural volume, 0-29/y; median 7/y). The MVRepair percentage increased from 48% in 2001 to 63% in 2013 (P < .001). MVRepair rates varied widely among centers; center volume explained only 19% of this variation after adjustment for case mix (R2 = 0.19, P = .005). Unadjusted 30-day and 1-year mortality rates were lower after MVRepair than after MVReplace (3.5% vs 4.8%, P = .04; 9.8% vs 12.1%, P = .02). Among the propensity-matched patients (n = 2520), 30-day and 1-year mortality were similar after MVRepair and MVReplace. In the propensity-matched primary degenerative subgroup (n = 664), unadjusted long-term mortality for up to 10 years postoperatively was lower after MVRepair (28% vs 37%, P = .003), as was risk-adjusted long-term mortality (hazard ratio, 0.78; 95% confidence interval, 0.61-1.01).
CONCLUSIONS: In the VA Health System, mortality after MV operations is low. Despite the survival advantage associated with MV repair in primary mitral regurgitation, repair is infrequent at some centers, representing an opportunity for quality improvement.
During cardiac surgery there is an unmet need for safe transfer of responsibility for patient oxygenation back and forth from the anesthesia to the perfusion teams. Prior to cardiopulmonary bypass (CPB), lung ventilation is performed by the anesthesia machine ventilator and is the responsibility of the anesthesia team. During CPB, lung ventilation is halted and oxygenation is performed by the CPB oxygenator and perfusion team This recurrent transfer throughout the procedure introduces the rare but serious possibility of a "never event", resulting in the patient's lungs not being ventilated upon stopping the CPB and potentially leading to catastrophic hypoxemia. Monitors and alarms on the anesthesia and bypass machines would not be useful when the other device is operating so they are routinely put into a standby mode until needed. Consequently, in the event that the handoff is missed, there are no alarms to catch the situation. To solve this unmet need, we propose a novel interoperable, context-aware system capable of detecting and acting if this rare situation occurs. Our system is built on the open-source OpenICE framework, allowing it to seamlessly work with a variety of ventilator and bypass machines.